Science Wednesday: Good Neighbors

About the author: Aaron Ferster, a science writer in EPA’s Office of Research and Development, is a regular contributor to Science Wednesday.

Last Spring, a pair of barred owls took up residence in the upper reaches of a tree just past the edge of our yard. They announced their presence during dinner one warm evening, a series of deep hoots in a pattern birders describe as “who-cooks-for-you.”

We caught a brief glimpse of one as it leaned off its perch and in a long, silent swoop faded into the shadows of the woods behind our house, disappearing like a ghost.

The owls didn’t disappear for long. The girls soon discovered a trove of owl pellets beneath the roost. By picking the pellets apart we learned what the owls were eating. Sometimes there were crayfish claws or fish scales, but the owl’s main course must have always included small mammals. Every pellet contained the tiny white vertebra and jaw bones of mice.

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Curtis Tackett adds a handful of sunflower seeds to one of the small, humane traps the survey team sets to survey mammal diversity. After examining the small animals, the team sets them free. (Click image to enlarge.)

Could owls and other wild neighbors be good for health by reducing the relative abundance of tick-infected mice? Last week I got to tag along with a team of Yale researchers surveying mammal diversity in the forests of Connecticut, part of an EPA-funded effort to explore just such questions.

Naturally, the team is taking a much more scientific approach than sifting through a handful of owl pellets. Instead, they set out small aluminum traps to humanely capture a representative sample of the local small mammal population.

Every critter caught was identified, ear-tagged (if not previously captured, a regular occurrence), and weighed. Before they were set free, each animal was thoroughly inspected and any black-legged ticks found were collected for further analysis. After the first day, we joined forces with another team conducting a similar survey of birds, part of an ongoing population study now sharing their efforts with the Yale team.

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Field coordinator Kim Tsao carefully examines each a white-footed mouse, counting and removing black-legged ticks for further analysis for the bacterium that causes Lyme disease. (Click image to enlarge.)